55th International Astronautical Congress 2004 - Vancouver, Canada

IAC-04-IAA.3.8.2.01

THE SPACE ELEVATOR DEVELOPMENT PROGRAM

Bradley C. Edwards Carbon Designs, Inc., United States [email protected]

ABSTRACT

For 40 years, the space elevator has been a concept in science fiction and appearing occasionally in technical journals. Versions of the space elevator concept have generally been megalithic in design. However, recent advances in technology and new designs for an initial space elevator have presented a much smaller and a more realistic version that has created a renewed interest in serious technical study. There are now over a dozen entities and hundreds of engineers and scientists with active research related to the space elevator. The activity includes conferences, engineering competitions, extensive media coverage, international collaborations, publications and private investment. These activities are rapidly expanding with the number of publications in 2004 nearly ten times the total for the prior forty years. INTRODUCTION

The space elevator concept has been around for spacecraft, the power delivery system, many years (Tower of Babel, Jack and the challenges to the system, etc. Beanstalk, Clarke’s Fountains of Paradise, Robinson’s Red Mars) and between 1960 and The basic design presented in the NIAC work 1999 a few technical studies addressed the has stressed simplicity Ð a single, small, static basics of the system (Moravec, 1977; Isaacs, ribbon with mechanical climbers that ascend 1966; Pearson, 1975; Smitherman, 2000). These using conventional electric motors (figure 1). studies addressed the oscillations inherit in the The design implements conventional technology system, the taper requirements, and the general with little or no development wherever possible. difficulties but did not cover most of the technical The design is easy to grasp and analyze and details of construction and operation. may present a reasonable first system though may not present the optimal final design for In 2000, Edwards published a unique design for future generations of elevators. This initial effort the space elevator and followed this publication completed with $570,000 in funding has been the with an overview engineering funded by NASA’s catalyst for variant designs and additional Institute for Advanced Concepts (NIAC). The studies. final report from the Phase I effort and book resulting from the Phase II effort (Edwards, The initial effort also generated a template for 2003) outline the basics of a space elevator. defining the challenges and where research and These publications go through the basic ribbon engineering were most critically needed. Some design, the climber design, the deployment items such as the anchor station have been viewed as straightforward and understood in 55th International Astronautical Congress 2004 - Vancouver, Canada

Figure 1: Illustration of the first space elevator illustrating the various components. Insets from left to right: anchor station with power beaming station, carbon nanotubes, underside of climber showing the power beaming component, the upper end of the elevator with the initial deployment spacecraft and climber as counterweights. (Image from Discover Magazine) terms of current technology where as other are a new development (Li, 2004) though CNT components, such as the ribbon and system composite fibers have been made with as high dynamics, are unique and considered as 60% CNTs, strengths comparable to steel challenges. By defining the challenges the (5% CNTs by weight) and kilometers in length. problem has been broken down into pieces that The high-strength material being the primary can be investigated by individuals or groups. hurdle to construction it has also become the This accessibility of the problem has spawned focus of several efforts. growing interest in engineering and research communities. For example, in 2000, a search on The ribbon design and deployment are being re- the Internet for ‘space elevator’ would have examined in terms of possibly building the ribbon produced several hundred links. The same by attaching full width segments end-to-end search today will return over 150,000 links. instead by of the baseline increasing the width by splicing additional ribbons onto an initial small The primary technical hurdle for construction of ribbon. the space elevator is the production of the high- strength material with a tensile strength of 100 The system dynamics has also become an active GPa. At the current time, carbon nanotubes area of study due to its ease of entry. The (CNTs) have been measured with tensile dynamics that are now being investigated range strengths of 200 GPa. CNTs have been spun into from the smallest scale (individual fibers) to the yarns of pure carbon nanotubes and have been largest (finite element modeling of the full 62,000 implemented in composite fibers. The spun fibers mile ribbon). Small-scale dynamics revolve 55th International Astronautical Congress 2004 - Vancouver, Canada

around the degradation of the ribbon Trade studies are beginning to examine the components at the individual fiber and possibility of using a moving looped ribbon, interconnect level. Primarily this pertains to oscillating ribbon, or sets of pulleys. breakage of individual fibers in the ribbon and how the ribbon responds. Large-scale Due to the activity there has also been an dynamics involve the oscillations, profile increased need for a detailed overall systems variations and how the ribbon generally engineering of the program. The efforts to date responds as a system. have been disjoint and independent. Efforts to coordinate the efforts will result in a more The climber, being a straightforward mechanical efficient development program. system, has also attracted interest in the form of engineering competitions and detailed design To lay out the work in progress and how it is studies. The various designs now being being addressed the space elevator considered include the baseline tread system, development program can be discussed by a set pinching rollers, and offset rollers. Few new of topics: designs for the power transmission have been 1. Research groups presented. 2. Research activities 3. Public interest With the increasing interest there has also been 4. Private interest a healthy re-examination of the baseline design. 5. Complimentary development RESEARCH GROUPS

INSTITUTE FOR SCIENTIFIC RESEARCH together past work and current efforts into a (ISR) / NASA’S MARSHALL SPACE FLIGHT database and attempt to illustrate the priority CENTER (MSFC) issues and the solutions. This framework for data archival and trade-off evaluation is important for effective management of a project ISR/MSFC is slated to receive $2.485M for 2004 with the size and complexity of the space to conduct Pre-Phase A / Phase A engineering elevator. studies. This funding is a congressional appropriation that will be directed by NASA’s TASK 2: HIGH STRENGTH MATERIALS Marshall Space Flight Center. The funding for the 2004 fiscal year arrived at ISR/MSFC for use in ISR/MSFC will be putting a small fraction of their mid-August, 2004. funds toward development and evaluation of high strength materials. Part of this will be to The ISR/MSFC development effort has six tasks: organize a CNT materials workshop which may 1. Systems engineering happen in November, 2004, in Kentucky. 2. High strength materials 3. Ribbon dynamics TASK 3: RIBBON DYNAMICS 4. Ribbon design ISR/MSFC has begun to compile the information 5. Prototype climber on the drivers in the dynamics area. These 6. Distribution of Results include: atomic oxygen, debris, electric and magnetic fields, radiation, orbital dynamics, and These tasks were selected as the most critical thermal loads. Complete simulations are being from either the program or technology developed to understand quantitatively how development perspective. these drivers will affect the ribbon at the various scales. This work is in collaboration with David TASK 1: SYSTEMS ENGINEERING Lang (see below). The interactions and interdependence of the various space elevator subsystems and driving TASK 4: RIBBON DESIGN factors have not been quantified in detail and Utilizing the results of the ribbon dynamics compiled for easy access. ISR plans to bring efforts, ISR/MSFC plans to build and test 55th International Astronautical Congress 2004 - Vancouver, Canada

segments of ribbons with materials of varying The LANL radiation studies have found that there strength and stiffness as well as ribbons with will be operational challenges to transporting varying interconnects. The tests will be used to humans on the space elevator unless the understand what issues will arise as higher- climbers can move more quickly or be shielded. strength material is used. One of the main issues Solutions for this problem are being studied. will be the recoil dynamics of broken fibers and where the stored energy goes. In conventional The LANL studies on solar power satellites have materials this is not a problem but at the tensions found that the space elevator could be used in the space elevator the stored energy could be effectively to construct an economically released in ways that could cause more serious competitive system for delivering clean energy collateral damage. By testing and modeling the for terrestrial uses. ribbons with increasing strength ISR/MSFC hopes to design a ribbon that readily handles the energy release.

TASK 5: PROTOTYPE CLIMBER In this task ISR/MSFC plans to construct several small prototype climbers and begin quantifying the issues. The first two prototypes are under construction with different teams and different thrusts. The tracking and overall design issues are the first being addressed (see figure 2).

TASK 6: DISTRIBUTION OF RESULTS ISR/MSFC started pushing to finish Pre-Phase A efforts and begin Phase A level work. The effort plans to distribute the results of work in the form of conferences, reviewed papers and access to the systems database being produced.

LOS ALAMOS NATIONAL LABORATORY A set of of researchers at Los Alamos National Laboratory (LANL) has acquired internal funding for several basic studies and to support conference organization. These efforts at LANL are augmented by personal commitment extending beyond the standard work hours. Figure 2: Model of a complete climber system. The Several efforts are being pursued at LANL insert shows the details of the drive system. including: 1) the viability of solar power satellites using the space elevator, 2) the radiation OTHER GROUPS environment and how it affects the operation of Several other groups have begun research at the space elevator, 3) dynamics of the system, various levels. These include Spaceward, X and 4) overall applications of the space elevator. Tech, Liftport, MIT, and individuals.

RESEARCH ACTIVITIES

CONFERENCES June 2004: Washington D.C. Each was 2-3 days There have been three conferences dedicated to with 70 to 100 participants. Dedicated sessions space elevator efforts. They occurred in August at larger international conferences have also 2002: Seattle, September 2003: Santa Fe, and begun to appear. The first of these sessions will 55th International Astronautical Congress 2004 - Vancouver, Canada

be in Vancouver at the IAF/IAC 2004 conference, previously on the subject. Many of these articles the second will be at the Space Exploration 2005 are in the proceedings of the 3rd Annual Space conference in Albuquerque in April 2005 and Elevator conference and available through the additional ones will occur at the IAC/IAF in 2005. Institute for Scientific Research. Proceedings In addition, the space elevator is becoming a will also be published for the other large regular topic presented at various technical conferences mentioned above. In addition to conferences. published journal articles there are books in progress on the systems engineering of the Publications space elevator, a updated version of the original The number of published technical articles on the The Space Elevator, and several general interest space elevator in the last year (~50) and in the books on the development of the space elevator. coming year (~80) will be over ten times the total number of technical journal articles published PUBLIC INTEREST

General public interest in the space elevator has in the number of message boards now operating also grown dramatically. In the last couple years with specific discussions on the space elevator. the space elevator has appeared as a prominent These include National Space Society, Yahoo, article thousands of times around the world. Slash.dot, Space.com, and Liftport. Initially the space elevator appeared in technically-oriented publications (Ad Astra, Tech The large space advocacy groups are also TV, Science News, Space.com). Recently, the taking an interest in the space elevator. The space elevator has appeared in more general National Space Society has come out and stated interest or business media (Wall Street Journal, definitively that they strongly support the New York Times, Inc., Fox News). development of a space elevator and will do whatever they can to make it happen. Articles on the space elevator have appeared in: − CNN Live - Science News (cover) The space elevator concept has also been the − Fox News - New York Times center of several art exhibits in Europe (Utopia − BBC - Ad Astra (cover) Station), considered for documentaries and is − Inc. - Wall Street Journal now a component of the movie script, The Ark, − Space.Com - Wired Magazine by Alan Chan. − MSNBC - Canadian National Post − Tech TV - Discover (cover) Educational interests With the growing research interest in the space − Seattle Times - The Tonight Show elevator there has been an increase in the Another indication of public interest is the number of students (K-12, college, graduate) distribution on the Internet. As stated above the that are actively getting involved in space the number of links found in a Google search of elevator related activities. These activities are ‘space elevator’ has increased from under two unorganized and involved students conducting hundred in 1999 to over 150,000 today. Part of research reports on the space elevator, science this increase is likely due to improvements in the fair activities, and thesis work related to various search engine. Public interest can also be seen subsystems. PRIVATELY FUNDED EFFORTS

CARBON DESIGNS, INC. directed at advancing the current state-of-the-art Carbon Designs is a privately funded research in materials to achieve materials with tensile entity to develop high-strength materials. The strengths of between 30Gpa and 50Gpa in 2005. first round of funding is expected to begin in Follow-on funding is expected to increase this September 2004. The initial efforts will be strength in the second year. The commercial 55th International Astronautical Congress 2004 - Vancouver, Canada

focus of this effort will allow for continued modes of the elevator and the required impulses funding prior to implementation of the material in to induce each. the space elevator. Carbon Designs was co- founded by the author. Pete Swan has been working to lay out the systems engineering aspects of the space SPACEWARD / ELEVATOR: 2010 elevator. He has begun defining the overall Spaceward, a recently initiated non-profit structure and architectures required for a project organization off-shoot of Gizmonics, is dedicated like the space elevator. to producing the Elevator: 2010 climber competition. To be held in June, 2005, the Roger Gilbertson, The Robot Store, has worked competition will pit university and individual to implement a small climber competition at the efforts against each other in a speed (>1m/s Robotics Society of America meeting. This over 100m vertical altitude) and carrying capacity climber competition has had three successful (~100 kg climbers) competition with the winner years of operation and produced small climbers receiving prizes in the tens of thousands of that work at a scaled down level of what is dollars. The competition is expected to required in the real system (see figure 3). demonstrate the viability of the climbing and laser power beaming components.

Spaceward also supports research activities on specific engineering aspects of the space elevator including ribbon and deployment scenarios.

MARC BOUCHER / SPACEREF Marc Boucher, founder of SpaceRef, constructed a website dedicated to the space elevator at www.spaceelevator.com. This site has space elevator resources and news.

LIFTPORT A private group working to toward the realization of a space elevator. Liftport hosts a site with news and resources on space elevator activities. Liftport states on their website that they are collecting funds and will be supporting high-strength material development efforts.

INDIVIDUALS David Lang has been conducting dynamics Figure 3: Climber built by Jack Buffington that won modeling of the space elevator using a the 2004 ribbon climbing competition of the customized version of the GTOSS simulation Robotics Society of America. The climber is code. GTOSS is a finite element analysis code shown with its photovoltaic arrays folded up. that has been utilized in conventional space During ascent the arrays fold down. tether modeling and has demonstrated accuracy in that situation. The customized version of Andrew Price and Blaise Glassend both support GTOSS for the space elevator simulation has a websites with space elevator information and larger set of finite elements and works in both efforts. Each has also been conducting dynamic and static situations. Lang has used research in specific areas of the space elevator the code to illustrate the oscillation and failure in terms of deployment and dynamics. 55th International Astronautical Congress 2004 - Vancouver, Canada

COMPLIMENTARY DEVELOPMENT

The space elevator system utilizes a diverse set of technologies so advancements in related fields can greatly benefit the space elevator effort. The baseline design for the space elevator attempts to maximize the use of these off-the-shelf technologies. Several of the recent advancements are illustrated below.

New laser designs The baseline space elevator design has a laser power beaming system to deliver power from Earth to the climbers. Recent advancements in lasers may simplify this system. The solid-state laser being developed at Boeing (Vetrovec, 2004.) uses a disk of active material to produce high continuous power (figure 4). A single 1 kW laser has been produced and tested with Figure 6: Illustration of multiple 1kW disk laser excellent results (figure 5) and current proposals modules combined into a single large laser plan to construct a 100kW laser by combining (Vetrovec, 2004). individual modules (figure 6). The wallplug efficiency is 30% and the operating wavelengths Carbon nanotubes are in the 800 to 1000 nm range. The National Nanotechnology Initiative (NNI) was created to speed up development of a number of nanoscale related technologies. The 2004 funding level for NNI is $990M and spread across a dozen federal agencies. One of the technologies being pursued under the NNI is carbon nanotube composites. The programs that are part of the NNI include the Small Business Technology Transfer (STTR), Small Business Innovative Research (SBIR) and Advanced Technology Program. Funding levels in these programs range from $600,000 to $2 million spread out over two years or longer. These Figure 4: Image of a single 1 kW disk laser module. levels are insufficient to move large (Vetrovec, 2004). developments forward. With the current composite market at $40 billion annually it is more likely that the carbon nanotube composites will be developed independently for golf clubs, tennis racquets, and aerospace rather than in the NNI or for the space elevator.

Recent reports on health issues related to CNTs have been published. These reports include several animal-based studies and individual reports from a worker at a nanotube production facility. Some initial reports indicate serious health hazards while others indicate that the Figure 5: Image of a 1kW disk laser during risks are minimal. This is a critical issue for the operation (Vetrovec, 2004). composite industry so it is expected that the 55th International Astronautical Congress 2004 - Vancouver, Canada

number and accuracy of these studies are including habitat modules will benefit the space expected to increase in the coming years and elevator in terms of allowing rapid development clarify the health issues related to CNTs. of space and producing detailed estimates of cost and complexity of commercializing space. Applications Technology The disconnect between the NASA effort and NASA’s exploration program is driving toward a what will be needed in applications using the sustained presence in space with a station on space elevator is in the much more expensive the moon and men on Mars. The required construction required for rocket based systems. technology developments for this program

TRENDS AND UNIQUE ASPECTS OF THE SPACE ELEVATOR DEVELOPMENT

One of the unique aspects of the space elevator required tests will take years. The effort will is the speed at which it has gone from being need to grow considerably in the near future for considered a strictly science fiction concept or the space elevator to be built in the next 15 distant possibility (1999) to a concept seriously years. considered for near-term construction (2004). Most of this change has occurred since Future work on the space elevator could go in completion of the NIAC study and release of the several directions. Private organizations are book, The Space Elevator, in early 2003. This currently pushing development with the only rapid change is a result of clarifying the public funding coming through a congressional engineering arguments for construction of the appropriation (ISR/MSFC). This disparate level of space elevator. interest is in spite of many more briefings to government agencies than to private However, the construction of a space elevator is organizations. Governmental briefings have a large program and will require a much larger included perhaps a dozen at NASA headquarters effort than what currently exists. Estimated and various NASA centers, DARPA, Air Force costs for construction are around $10 billion for Research Laboratory, Air Force Space Missile the first space elevator and a fraction of this for Center, NRO, NSA, Rayburn House Office subsequent systems. Development costs for the Building and personal invitations to the space space elevator should then be expected to be elevator conferences. In addition, proposals in around 5% to 10% of the final cost or $500 response to NASA’s Exploration Systems Broad million to $1 billion. The other aspect of this is the Area Announcement for examining a space schedule for development. The engineering of elevator based exploration program were not integrating the components and conducting the selected for funding. CONCLUSIONS

Recent developments in the design of a viable a handful in 1999 to hundreds today at many space elevator have led to a dramatic increase in institutions. The activity includes dedicated the amount of activity and research conducted in conferences, publications, media coverage, and this area. The number of researchers private investment. investigating the space elevator has grown from

REFERENCES

Clarke, A.C. 1978. The Fountains of Paradise. Clarke, A.C. 1979. The Space Elevator: ‘Thought New York: Harcourt Brace Jovanovich. Experiment’, or Key to the Universe. Adv. Earth Oriented Appl. Science Techn. 1:39. 55th International Astronautical Congress 2004 - Vancouver, Canada

Industrialization of Space, San Francisco, Ca., Edwards, B. C. 2000. Design and Deployment of October 18-20, also Journal of the Astronautical a Space Elevator. Acta Astronautica. In Print. Sciences 25, October-December.

Edwards, B.C. and Westling, E.A. (2003) The Pearson, J. 1975. The Orbital tower: a Space Elevator, Spageo, San Jose, ISBN 0- spacecraft launcher using the Earth’s rotational 9726045-0-2 energy. Acta Astronautica 2:785.

Isaacs, J.D., Vine, A.C., Bradner, H., and Smitherman Jr., D. V. 2000. Space Elevators: An Bachus, G.E. 1966. Satellite Elongation into a true Advanced Earth-Space Infrastructure for the ‘Sky-Hook’. Science 151:682. New Millenium, NASA/CP-2000-210429.

Li, Y. L., Kinloch, I. A., Windle, A. H., Science Vetrovec, J., Shah, R., Endo, T., Koumvakalis, A., Express, March 2004. Masters, K., Wooster, W., Widen, K., and Lassovsky, S., SPIE LASE 2004 Conference, Moravec, H. P., 1977, A Non-Synchronous Orbital San Jose, CA, January 25-30, 2004. Skyhook, 23rd AIAA Meeting, The